Noble metal containing catalysts are used in many hydrocarbon conversion processes. One such process is catalytic reforming. Catalytic reforming is carried out using a feedstock containing paraffins and naphthenes. The reactions which take place during reforming include: dehydrogenation of naphthenes to aromatics, dehydrocyclization of paraffins, isomerization of paraffins and naphthenes, dealkylation of alkylaromatics and hydrocracking of paraffins to light hydrocarbons.
It is well recognized that the catalysts used for reforming, e.g., platinum dispersed on zeolites, are sensitive to sulfur in the feedstream. It is known that sulfur poisons the metal catalyst resulting in low activity, selectivity and stability. For example, sulfided metals have a tendency to agglomerate very quickly. Attempts to improve the sulfur tolerance of metal catalysts have had very little, if any, success. For example, U.S. Pat. No. 5,366,617 discloses a reforming catalyst containing a nonacidic L-zeolite, a noble metal and a non-noble Group VIII metal which is concentrated extrinsic to the pores of the zeolite. It is stated that the catalyst has improved activity in the presence of 400 ppb of sulfur. Another reference is U.S. Pat. No. B1 4,456,527 which discloses using a catalyst comprising a large pore zeolite containing at least one Group VIII metal. The sulfur concentration must be below 100 ppb. It is clear from these references that although they claim to have an improved sulfur tolerant catalyst, the improvement is very slight and processes or guard beds must be used in order to reduce the sulfur content in the feedstream from several thousand parts per million to the part per billion range. Accordingly, a strong need exists for a catalyst which can tolerate exposure to sulfur in high concentrations, i.e., 1,000-30,000 ppm.
In reply to this need, applicants have developed a catalyst which shows very good activity even when the feedstream contains about 30,000 ppm of sulfur. This catalyst comprises two components. The first component is a Group VIII metal dispersed on an inorganic oxide support, while the second component is a metal phthalocyanine dispersed on an inorganic oxide support. The two components can be mixed together in one bed or be present as two beds. Which bed the hydrocarbon is contacted with first will depend on the particular process. There is no indication in the art that a combination of a noble metal dispersed on a support and a metal phthalocyanine on a support would result in a hydrocarbon conversion catalyst with superior sulfur tolerance.